TCT: Stent Thrombosis Rates Equal Two Years Out

Action Points

Explain to interested patients that the study was not specifically designed or statistically powered to compare long-term stent thrombosis rates between stent types in the trial but may be the best randomized evidence to date for this measure of safety at two years.

Note that this study was presented at a conference. These data and conclusions should be considered preliminary until published in a peer-reviewed journal.

SAN FRANCISCO -- Drug-eluting stents yield the same rate of stent thrombosis as bare-metal ones in acute MI patients at two years due to late catchup with the drug-eluting variety, according to an analysis of the HORIZONS-AMI trial.

Late catchup with the drug-eluting variety brought two-year definite or probable stent thrombosis rates to an identical 4.1% for both the Taxus paclitaxel-eluting stent and Express bare-metal stent (P=0.99), Roxana Mehran, MD, of Columbia University in New York City, and colleagues reported.

The results were reassuring for the safety of drug-eluting stents, said Mehran, who presented the results at a press conference here at the Transcatheter Cardiovascular Therapeutics meeting.

"I don't think we've known about the safety of drug-eluting stents at all beyond a year in a large enough randomized study until today," she said. "This is the first time we're going to learn we're okay."

Ajay Kirtane, MD, SM, of Columbia University Medical Center/New York-Presbyterian Hospital in New York City, agreed that this highly anticipated result was reassuring.

Although the trial was not powered for stent thrombosis as a secondary endpoint, it is the first large randomized trial evidence on two-year safety between drug-eluting and bare-metal stents in acute MI, said Kirtane, who moderated the press conference.

"A lot of people have been waiting to see what would happen," he said. "Most clinicians assume that late stent thrombosis only occurs with drug-eluting stents and not with bare-metal stents, but we do clearly see it with bare-metal stents."

At one year in the HORIZONS-AMI (Harmonizing Outcomes with Revascularization and Stents in Acute Myocardial Infarction) trial, the paclitaxel-eluting stent showed a lower stent thrombosis rate than its bare-metal comparator.

However, the curves converged soon thereafter, yielding an identical result at year two of the planned five-year follow-up.

After emergency coronary angiography, patients had also been triaged to medical therapy or revascularization.

The 95.5% triaged to primary percutaneous coronary intervention were randomized to a paclitaxel-eluting or bare-metal stent.

For the primary stent safety endpoint, there was no difference in the composite death, reinfarction, stroke, and stent thrombosis rate between groups at two years (11.0% versus 11.2%, HR 0.98, P=0.90).

Ischemic target lesion revascularization -- the primary efficacy endpoint of the stent comparison -- rates jumped after the 13-month angiographic follow-up in both groups. But they remained significantly lower with the drug-eluting stent (6.8% versus 11.6%, HR 0.58, P<0.001) without evidence of late-catch up.

Mehran cautioned that these stent efficacy results should be considered hypothesis generating given the "possible influence of routine angiographic follow-up."

She also noted that the results aren't a rationale for universal drug-eluting stent use. "It's really important to take a very good history of the patient and their ability to take prolonged dual antiplatelet agents."

The study was supported by the Cardiovascular Research Foundation -- sponsor of TCT -- with grant support from Boston Scientific and The Medicines Company.

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